How should APCH clear an aircraft below 6,000 feet?

The correct approach for clearing an aircraft below 6,000 feet is to do so when the aircraft is established on the assigned route. This practice ensures that aircraft are safely guided along their intended path while in a critical stage of their descent and approach.

Establishing on the assigned route allows the controller to confirm that the aircraft is properly aligned and can safely operate within the controlled airspace, particularly when descending. This step is crucial for maintaining safe separation from other traffic and for minimizing potential conflicts with other aircraft that are also transitioning through the same airspace.

The other options do not follow established protocol for safe aircraft operations. Clearing an aircraft upon first contact could be premature if the aircraft is not yet on the correct route or altitude, which may compromise safety. Waiting until the aircraft reaches cruising altitude before issuing a clearance is not practical during approach and could lead to unnecessary delays or altitude changes. Finally, issuing an Expected Further Clearance (EFC) time is useful in certain situations but is not a prerequisite for issuing a clearance for descent below 6,000 feet, as it is more about providing traffic management and not directly linked to clearance protocols for approach.